Method of positioning a tubular element in a blood vessel of a person

ABSTRACT

A method of positioning a tubular element inside a main blood vessel of a person. The tubular element has a main tube with one or more side openings and a transport wire extending through each side opening. A fixator being positioned in each branch vessel and the corresponding guide wire being attached to the corresponding transport wire, whereby re-routing of the guide wire is performed by pulling the transport wire to have the guide wire extend from the fixator through the corresponding side opening and to the outside of the person. This re-routed guide wire may be used for positioning the tubular element or guiding additional elements from the tubular element and into the branch vessel.

The present invention relates to a method of positioning a tubularelement in a blood vessel of a person and more particularly a manner ofpositioning a fenestrated, branched or multiple branch stent graft in aperson.

The use of graft stents in persons is a routine technique foralleviating e.g. aneurisms which could otherwise burst and cause massiveinternal bleedings and death. The grafts, when positioned, form internalwalls or structures in the blood vessels and thus alleviate the pressurecausing and bursting the aneurisms.

The positioning of a fenestrated or branched graft is difficult in thatthe opening into the branch vessel in which the branch of the graft isto be positioned may be more or less clogged, may be positioneddifferently from person to person, and the branch vessel may be angled,relative to the main vessel, differently from person to person.

Thus, when positioning the graft inside the main vessel, it is difficultto have the graft branch or side opening direct or extend directlytoward the branch vessel and/or into this branch vessel. If the graftbranch is positioned a bit off or angled a bit off, it is extremelydifficult to direct the graft opening or branch toward or into thevessel branch.

One solution to the positioning/angling has been to perform detailedtomography of the blood vessels of the person and produce individualizedbranched grafts for each person. Such grafts, however, are extremelyexpensive and do not solve the difficulties caused by extensive bloodclogging in the aneurisms. Also, the rotational positioning thereof, tohave the branches point toward the respective branch vessels, is basedon making two markings on opposite sides of the graft overlap.

In a first aspect, the invention relates to a method of positioning atubular element having:

-   -   a main tube having an inner space defined between a first and a        second end portion along a longitudinal axis of the main tube        and at least an end opening at the first end portion from the        inner space to surroundings of the main tube,    -   a side opening positioned between the first and second end        portions between the inner space and the surroundings,    -   a transport wire having a first part, which extends from the        inner space and out of the tubular element through the end        opening, and a second part, which extends from the inner space        and out of the tubular element through the side opening,        in a main blood vessel, having a branch vessel, of a person or        animal, the method comprising:    -   providing an assembly having a guide wire and a fixator adapted        to be releasably attached to an inner side of the branch vessel,        the fixator being attached to the guide wire, which guide wire        has a distal end for introduction into the branch vessel and a        proximal end,    -   introducing the fixator into the branch vessel, via the main        blood vessel, and fixing the fixator to the branch vessel,    -   providing the tubular element inside the main blood vessel so        that the first part of the transport wire is engageable from        outside the patient,    -   fixing or attaching the second part of the transport wire to the        guide wire, and    -   pulling the first part of the transport wire to have the guide        wire extend from the fixator through the side opening, the inner        volume, and the end opening.

In this context, a tubular element is a hollow element having aninternal space or volume and openings between the internal volume andthe surroundings of the tubular element. In this context, thesurroundings is the space or volume outside the tubular element notforming part of the internal volume.

The tubular element extends along a longitudinal axis which may bestraight, bent, curved or have any shape which may depend on or bedefined by e.g. the shape of the main blood vessel (see further below).

Preferably, the main tube has a wall defining an end opening at each endportion and through which the longitudinal axis extends, where the sideopening is formed in the wall so as to open is into the main volume froma lateral position or angle, i.e. an angle not identical to thelongitudinal axis at the longitudinal position of the side opening. Aswill be made clear further below, the tubular element may have anynumber of side openings. The side opening(s) may be positioned at anyposition in the main tube and in relation to any other side opening(s).

The tubular element may comprise means for fastening the main tube tothe main blood vessel of the person if desired. Such means may be hooklike or spike like elements for travelling into a wall of the bloodvessel or may be expanding elements or hook like elements adapted toexpand and/or engage the inner side of the blood vessel, such asirregularities thereof.

Usually, the tubular element will resemble, mimic or copy the structureand overall shape of the main vessel. However, the tubular element mayhave a smaller cross section, perpendicular to a longitudinal axisthereof, in order to e.g. treat aneurisms, for example, which increasethe blood vessel cross section. Then, the positions of the sideopening(s) may preferably correspond to the position(s) the branchvessel(s) in order for blood, subsequent to the deployment of thetubular element, to be able to flow from the inner volume and into thebranch vessel(s).

Preferably, the tubular element is formed of a material which is atleast substantially impermeable to blood, as it may have a desiredfunction of forming a new blood vessel or at least forming an inner,pressure reducing, element in a blood vessel. Thus, preferably, bloodflow from the surroundings (when deployed) of the tubular element andinto the inner volume is possible only via the openings.

The tubular element may be collapsible and/or expandable in order to bemore easily positioned within the blood vessel(s) of the person/animal.

The transport wire and the guide wire may be any type of wire adapted to(or useful for) be introduced into a blood vessel of a person.Presently, a guide wire and/or transport wire is an elongated elementadapted to be introduced into a blood vessel of a person. Often, aguide/transport wire has a slippery surface, such as a hydrophilicsurface, so as to be introduced into the blood vessel without harmingthe vessel. Typical guide/transport wires for catheterization have acircumference of between 0.14 and 0.89 mm. However, any thickness may inprinciple be used. The guide/transport wire may be made of a polymer ora metal/alloy, such as nitinol.

The guide wire may be of a type having an outer sleeve which is ratherpliable and an inner, stiffer, element which may be introduced into thesleeve, when the guide wire is desired more stiff and which may bewithdrawn, when the guide wire is desired more pliable.

According to the invention, the transport wire has a first partextending from inside the main tube and out of the tubular elementthrough the end opening and a second part extending from the innervolume and out of the tubular element through the side opening. Thus,the transport wire may preferably be pulled out from the tubular elementby puling any of the first and second parts. Preferably, the transportwire is a single, longitudinal element.

In the present context, the main blood vessel preferably denotes thelarger of the main blood vessel and the branch vessel. In manysituations, the blood vessels are arteries, where the main blood vesselthen provides blood flow toward and into the branch vessel.

Usually, the present fixator is for use in arteries of theperson/animal, such as the aorta or one of the arteries directlyreceiving blood from the aorta, but this is not a limitation. Thus, inone situation, the main blood vessel is the aorta of a person, where thebranch vessel may then be the visceral arteries and the aortic arcarterial branches. In other situations, the method may be used in thecommon iliac artery, and the internal iliac arteries.

In this context, the distal end of the guide wire is that intended to beintroduced into the blood vessel, whereas the proximal end is intendedto extend away from the branch vessel and in some embodiments (seefurther below) out of the person. Thus, the proximal end may also extendinto or be provided inside the blood vessel of the person but will thenbe the end introduced the latest or the end being closest, along theblood vessels, to the user/surgeon.

In the present context, the fixator is brought to fix/engage or attachitself to the blood vessel in any desirable manner. A preferred manneris a friction attachment by which the fixator purely by frictionattaches the blood vessel and thereby counteracts removal thereof alongthe axis of the blood vessel. A typical manner of obtaining a frictionengagement is to have the providing step comprise providing the fixatorinside the blood vessel in a collapsed form and thereafter allow thefixator to expand so as to contact the inner side of the blood vessel.Usually, an expanding fixator will expand to be limited by the innerdimensions of the blood vessel so as to exert a predetermined force tothe inner side of the blood vessel to stay in place.

Naturally, also other manners of engaging or, attaching to the bloodvessel are known, such as elements with small spikes or nails whichtravel into the blood vessel wall in order to maintain the element inthe desired position.

Preferably, the fixing/attaching/engaging of the fixator to the vesselwall is a releasable attachment so that the fixator may be repositionedor removed (see further below) during or after the procedure.

The step of providing the tubular element inside the main blood vesselmay comprise providing the tubular element therein in a fully collapsedor partly collapsed state, such as a state in which a cross sectionalarea or circumference thereof, perpendicular to the longitudinal axis,is smaller than in a fully deployed state, which is the final statewhich the tubular element is to maintain in the blood vessel. In thissituation, it may be desired to position the tubular element beforefully deploying it. This positioning may be a positioning along thelongitudinal axis or along the main blood vessel as well as a rotationalpositioning in order to have the side opening correspond, in position,to the branch vessel or at least an opening thereof into the mainvessel. When the tubular element is in the fully deployed state, it maycontact the vessel walls of the main vessel and thus be more difficultto reposition.

This positioning of the tubular element may be performed during thepulling step or after the pulling step by exerting a force to the guidewire so as to force the side opening toward the branch vessel in whichthe fixator is fixed.

Having thus positioned the tubular element, the method may comprise,pursuant to the pulling step, bringing the tubular element from thefully or partly collapsed state and to a fully deployed state in orderto e.g. fix the tubular element inside the main vessel.

Such tubular elements may be introduced into a blood vessel in acollapsed state while guided by a guiding catheter, brought to a partlycollapsed state while engaged or maintained in the partly collapsedstate, such as by the guiding catheter, and positioned, before beingreleased from the guiding catheter and allowed to obtain the fullydeployed state.

Having provided the tubular element within the main vessel, the firstpart is engageable from outside the patient. In a preferred embodiment,the first part extends to the outside of the patient, usually through apercutaneous arterial puncture, but if positioned inside a blood vesselof the patient, it is still accessible for e.g. snaring using anotherguide wire or a snaring catheter. This is standard procedure forendovascular surgeons.

The attachment of the guide wire to the fixator may be permanent orreleasable. Further below, a releasable attachment or restraining isdescribed which has a number of advantages.

The fixing or attaching of the second part of the transport wire to theguide wire may be an attachment of any type, such as a if one of thesecond part and the guide wire has a hook and the other a loop, or ifone of the second part and the guide wire has a claw or the like adaptedto engage, fix or grab the other, or, for example, if one of the secondpart and the guide wire has a snare. Often a snare is provided on a wirewhich may be withdraw into a catheter so as to fix an element extendinginto the snare. Additionally, the two wires may be attached to eachother using a third element, such as a clamp or the like, or they maysimply be tied to each other by e.g. a knot. In fact, the attachmentneed not be a fixing. If e.g. the second part has a snare, it may beguided, such as by pulling the first part and fixing the proximal partof the guide wire. In this manner the snare will move toward the branchvessel and when being sufficiently close thereto, the proximal part ofthe guide wire may be released so that the pulling of the transport wiremay re-route the guide wire which, due to the operation of the snare,will follow the snare to the outside of the person, as the snare slidesalong the guide wire as fixed by the fixator at the distal end thereof.

It is noted that a replacement of the transport wire with a subsequentwire, which is then pulled in order to re-track the guide wire will betantamount to performing the same operation using the transport wire.

The pulling step may comprise any manner of transporting, withdrawing,translating or moving the first part of the transport wire andconsequently the second part and the guide wire. Any means or method maybe used for this movement, such as an engine, a translating element, aspring or the like. A simple manner would be for a surgeon or the liketo pull the first part, if external to the person and otherwise engagedby another element, to obtain the overall result of the guide wirefinally extending through the branch tube and the main tube (usuallyalong the same path formerly occupied, by the transport wire). Thus, theguide wire may now be used for guiding elements through the main andbranch tubes and into or toward the branch vessel.

The present tubular element may be a simple tubular element havingmerely holes therein, such as the elements usually denoted a fenestratedgraft. Alternatively, the tubular element may have a main tube and oneor more branch tubes, such as the so-called branched grafts.

Thus:

-   -   the tubular element may comprise a branch tube attached to the        main tube and opening into the main tube, the side opening being        an opening from the surroundings into the branch tube, and    -   the second part of the transport wire then may extend from the        inner volume of the main tube and out of the tubular element        through the branch tube and the side opening.

In this context, the tubular element preferably has a main tube having,if having a circular cross section, a larger radius or, more generally,a larger cross section, than the branch tube, which may also have anydesired cross section.

Preferably, the main tube and branch tube are assembled, such as fixedto each other, if not provided as a monolithic element, in a liquid(typically blood) impermeable manner, so that liquid (blood) is not ableto escape from inside the main tube and to the surroundings of thetubular element through any interface there between. In addition,preferably, the main tube and the branch tube comprise at leastessentially liquid (typically blood) impermeable walls in order to e.g.be adapted to alleviate a blood pressure to the walls of the main bloodvessel. except via one of the openings of the main and branch tubes.Consequently, the tubular element preferably is at least substantiallyliquid impermeable except at the openings thereof.

One result of this is that the branch tube may now be directed toward oractually into the branch vessel, as it may be guided along the guidewire extending from the branch vessel and into the branch tube, duringor after the pulling step. Exerting a force to the guide wire,subsequent or under the pulling step, may force the branch tube towardor into the branch vessel. Secondly, elements may subsequently beintroduced into the branch vessel via the guide wire and the branchtube, such as when introducing a secondary tubular element intended toextend from the branch tube (such as be fixed to or engaging the branchtube) and into the branch vessel, such as further into the branch vesselthan the branch tube, may be obtained by using the guide wire as a guidefor the introduction of this secondary tube. This is described furtherbelow.

It is noted that if no branch tube is present, such as if a so-calledfenestrated graft is used, it is also possible to provide a secondarytubular element which is guided by the guide wire and which then isattached to or engages the main tube, usually at the side opening. Then,the secondary tubular element may be flared in order to seal the sideopening and so that it does not detach from the main tube and travelinto the branch vessel.

In general, the guide wire preferably has a length sufficient for it toextend out of the person after the pulling step. Then, the transportwire can be pulled or moved to outside the patient/animal and may thenbe discarded. Alternatively, the guide wire may extend part of the pathfrom the fixator to outside the patient and the transport wire, attachedto the guide wire will extend the remainder of the path. In thissituation, the combined/attached guide wire and transport wire mayperform the subsequent guiding operation.

In one embodiment:

-   -   the introducing step comprises the step of having the guide wire        of the fixed fixator extend to the outside of the person,    -   the providing step comprises having also the second part of the        transport wire extend to the outside of the patient, and    -   the fixing/attaching step comprises fixing or attaching the        second part to the guide wire outside the person.

This is a simple manner of obtaining a swift and secure fixing/attachingby performing it outside the body.

Especially in this situation, it is preferred that the introducing stepcomprises introducing the fixator into a blood vessel of a personthrough a percutaneous opening into a blood vessel, and wherein theproviding step providing the tubular element inside the main bloodvessel through the same opening of the person.

Alternatively, the fixing/attaching step may comprise fixing orattaching the second part to the guide wire inside a blood vessel of theperson. In this manner, shorter guide wire/second part may be used, asone thereof needs not extend to the outside of the person.

Another alternative would be to introduce different fixators throughdifferent blood vessels (such as from arteries in the person's arms orlegs), introduce a tubular element with multiple openings and multipletransport wires through one blood vessels and subsequently re-routetransport wires and/or guide wires to enable snaring and subsequently beable to introduce additional tubular elements, if desired, through theopenings though which the guide wires finally extend.

Having positioned the tubular element in the blood vessel(s), thefixator and the guide wire may be used for guiding further elements intothe main tube, the branch tube, the main vessel and/or the branchvessel.

However, in some situations, the fixator may be in the way of suchelements, especially when the branch vessel is not sufficiently long,such as if it divides into smaller vessels closely to the main vessel.In such situations, it may be desired to remove the fixator beforeintroducing such further elements. Alternatively, the fixator may becollapsed and these other elements be introduced over the collapsedfixator. As such further elements are usually adapted to be guided overa standard guide wire, the fixator could be collapsible to obtain afinal shape having an outer diameter corresponding to that of the guidewire. Thus, the guide wire could have a narrow portion adapted toreceive the fixator when collapsed.

In such situations, among others, the step of providing the assembly maycomprise providing an assembly in which the fixator may moveindependently of the guide wire, the assembly further comprising meanspreventing the fixator from travelling distally of the preventing meansand/or beyond the end of the guide wire,

the method further comprising the steps of, subsequent to the pullingstep:

-   -   removing the fixator while maintaining the distal end of the        guide wire inside the branch vessel, and    -   introducing another element along the guide wire.

Thus, the still positioned guide wire (or the guide wire attached to thetransport wire) may subsequently be used for introducing other elementsinto the branch vessel, such as filters, stents or grafts.

In fact, in a preferred embodiment, the introducing step comprisesintroducing another tubular element along the guide wire and positioningthe other tubular element so as to extend from inside the tubularelement (main tube and/or branch tube) and into the branch vessel.

This is especially useful when the positioning step comprisespositioning the other tubular element so as to cover an area of thebranch vessel where the fixator was fixed. In this manner, any vascularwall damage caused by the fixator may be covered by the other tubularelement so as to avoid blood clotting which may be caused by suchdamages.

In a particular embodiment, the main blood vessel has a plurality ofbranch vessels and wherein:

-   -   the tubular element has:        -   a plurality of side openings,        -   a plurality of transport wires, the first part of all            transport wires extending from the inner volume of the main            tube and out of the tubular element through the end opening            and the second part of each transport wire extending from            the inner volume of the main tube and out of the tubular            element through a separate side opening,    -   the providing step comprises providing a plurality of the        assemblies,    -   the introducing step comprises introducing a fixator into each        of the branch vessels (typically aortic branch vessels) and        fixing the fixators in the branch vessels,    -   the fixing/attaching step comprises fixing/attaching each guide        wire to a second part of a separate transport wire, where the        branch vessel in which the guide wire is fixed corresponds to        the second side through which the second part extends, and    -   the pulling step comprises pulling the first parts of the        transport wires so as to have the guide wires extend from the        individual fixators through the individual side openings and the        main tube and toward, preferably to, the outside of the patient.

The position correspondence preferably is a position or angling in whicha straight line from, such as perpendicularly to, the longitudinal axisor volume centre of the main tube may pass through a centre of the sideopening or branch tube and enter the branch vessel, preferably at acentral or longitudinal axis thereof.

Naturally, the plurality of transport wires may be replaced by a singleelement having a number of second parts extending as described but onlya single part, for example, connected to all second parts, and extendingas the first parts described.

It is clear that the tubular element may have a combination of one ormore second openings and one or more branch tubes, where a side openingis an opening into a tube between the end portions thereof.

Typically, all side openings are provided in, or all branch tubes extendfrom, the main tube, and a fixator is used for each side opening/branchtube, but this is not a requirement. A branch tube may extend fromanother branch tube, which extends from (such as is fixed to or thelike) the main tube. Also, a branch tube extending from the main tubemay have a side opening therein. The positioning of the fixators willalso make the positioning of this type of tubular element possible inthe blood vessels of a person.

In that situation, the other branch tube—or the intermediate branchtube—may not need a fixator in the corresponding blood vessel, as thefarther blood vessel into which the first branch tube is to bepositioned (or toward which the first branch tube is to extend) may havea fixator, which may also be used for positioning, the intermediatebranch tube.

In order for the fixator to fulfil its function as a fixator, itpreferably can maintain attachment to the inner side of the bloodvessel, when a pulling force of at least 0.1N is applied to the guidewire and the fixator.

The pulling of the guide wire may be intentional or non-intentional.Intentional pulling may be caused by re-direction of the guide wire orwhen directing additional elements into or toward the target bloodvessel along the guide wire. Also, usually real-time imaging of theposition of the fixator and other elements provided in the blood vesselsof the person is performed, so that the identity or position of afixator may be ascertained by pulling the proximal end or guide wire andidentifying the fixator moving due to the pulling. Naturally, thefixator may move without detaching from the blood vessel. Thisdetectable movement may be a slight sliding of the fixator within theblood vessel or simply the blood vessel moving as a result of the forceexertion.

In the present context, the maintaining of the attachment is a movementof no more than than 1 mm of the fixator in relation to the blood vesselwhen the force is exerted in at least 10 seconds, such as at least 30seconds, preferably at least 60 seconds. It is noted that no movement isdesired, as any movement of the fixator while attached may cause damageto the blood vessel.

Depending on the type of surgical procedure and a number of otherparameters, the fixator may be adapted to withstand a pulling force ofmore than 0.1N, such as 0.2N or more, preferably 0.3N or more, such as0.4N or more, preferably 0.5N or more, such as 0.6N or more, preferably0.7N or more, such as 0.8N or more, preferably 0.9N or more, such as 1Nor more, preferably 1.5N or more, such as 2N or more, preferably 2.5N ormore, such as 3N or more, preferably 3.5N or more, such as 4N or more,preferably 5N or more.

In the present context, the force which the fixator can withstand may bedetermined by testing the fixator in an animal blood vessel newlyharvested from the animal and when immersed in saline. Blood vesselshaving diameters like those in human beings may be harvested from sheep,pigs, calves or cows. During the testing, the saline is not pumpedthrough the vessel but kept more or less stand still. The force isexerted along a longitudinal axis of the blood vessel.

Clearly, a fixator will be adapted to be used in blood vessels of agiven size or having a size within a specified diameter range. Thus, thetesting should be performed under the same conditions, i.e. the fixatorshould be tested in a blood vessel having a size to which the fixator isprepared.

In a preferred embodiment, the fixator is designed to cover a minimumcross sectional area across the blood vessel to not to any substantialdegree disturb the blood flow through the fixator in the blood vessel,thus securing e.g. arterial supply to the end-organ, for example thekidney or the intestine.

One manner of determining a cross sectional area of the fixator is toproject the fixator onto a plane perpendicular to the longitudinal axisof the blood vessel. In this manner, a measure of the cross section maybe obtained, such as a percentage of the inner cross section of theblood vessel, but if e.g. a basket-type fixator of the type seen in FIG.1 is used, this cross section will not be that actually seen by theflowing blood. This basket-type fixator will have a fixing part engagingor attached to the blood vessel and which therefore is not relevant asto the cross section covered across the blood vessel cross section.However, this basket-type fixator may also have two end parts (proximaland distal parts) extending between the guide wire and the fixing part.These end parts will, in the projection, be overlapping and thus give anerroneous measure for the cross section seen by the blood. In thissituation, the cross section of that end part having the largest crosssection is a better measure for the cross section seen by the blood.

Preferably, the cross section(s) cover(s) less than 40%, such as lessthan 30%, preferably less than 20%, such as less than 10%, preferablyless than 6% of the vessel cross section.

Naturally, the fixator may have a non-thrombogenic surface quality andflow promoting hydrodynamic design. Non-thrombogenic surfaces may beobtained by electro polishing the surfaces, for example.

In one embodiment, the fixator has:

-   -   a deformable portion having a central portion adapted to attach        to the inner side of the blood vessel at a predetermined length        thereof, along a first longitudinal direction or axis of the        blood vessel,    -   a distal part attached to the deformable portion, and    -   a proximal part attached to the deformable portion.

Preferably, the deformable portion is adapted to exert at leastsubstantially the same force to the blood vessel along all of thepredetermined length when the pulling force of at least 0.1N is exertedto the guide wire and fixator.

Preferably one or both of the distal and proximal parts is adapted toengage the guide wire and/or a stopping means fixed to the guide wireand ensuring that the fixator does not pass or move distally of thestopping means. In a preferred embodiment, both the distal and proximalparts define apertures through which the guide wire is adapted to slide.Even more preferably, the stopping means is then fixed to the guide wireand is not able to travel through the aperture of one or both of thedistal and proximal ends.

Firstly, the central portion will usually be those parts of the fixatorwhich extend or are adapted to extend the farthest from a centrallongitudinal axis of the fixator. Usually, the blood vessels are tubularwith a circular cross section at least locally around the fixator, sothat the central portion normally is a tubular portion positioned thefarthest from the central axis. As will be described further below, thistubular portion need not have the same cross section along its entirelength.

Preferably, the predetermined length is between 2 mm and 30 mm, such asbetween 3 mm and 20 mm, preferably between 5 and 20 mm, such as between10 and 16 mm.

In one situation, the deformable portion forms a closed or unbrokensurface adapted to engage, touch or attach to the blood vessel. Inanother situation, the deformable portion comprises openings or holes.The deformable portion of the latter situation may be more easilycompressed and expanded and may be made of a weave or braided element.The openings or holes of the deformable portion may have a cross sectionof between 0.01 mm² and 10 mm², such as between 0.1 mm² and 1 mm². Thelarger the openings, the lower will the contact surface between theweave/braided element and the blood vessel wall, but the more easily maythe weave/braided element be compacted for introduction into the bloodvessel.

Naturally, a transition or intermediate part may be present between thecentral portion and the distal/proximal parts at which transition aslight force may be exerted to the blood vessel wall. Such parts are notrelevant in relation to the preferred embodiment, where the primaryfocus is to ensure that no local parts exist where an excessive force isapplied.

In this context, the exerting of at least the same force along thepredetermined length may mean that, along this length, the force exertedat all positions along the length will be within 20% of a mean value ofthe force exerted along the length, such as within 10% of the meanvalue, preferably within 5% of the mean value.

In another situation, the “at least the same force” may mean that, alongthe length, no position exists at which a force exceeding a mean valueof the force exerted along the length by more than 20%, such as 10%,preferably 5% of the mean value. Naturally, a lower force exertion is amuch smaller problem than an excessive force exertion.

Usually, the force exerted at a point along the direction will be thesame around the circumference of the central portion at a given positionalong the direction. Thus, the force may be summed or integrated aroundthe circumference for the individual points. If the force deviates morethan e.g. 10% around this circumference, individual angular positionsaround the direction may also be taken into account in order to identifyor prevent such force “peaks”.

In that or another embodiment, the fixator has:

-   -   a deformable portion having a central portion adapted to attach        to the inner side of the blood vessel,    -   a distal part attached to the deformable portion,    -   a proximal part attached to the deformable portion and being        translatable, along a second longitudinal axis, in relation to        the distal part, the distal part being positioned closer to the        distal end of the guide wire than the proximal part,        the central portion of the deformable portion circumscribing, in        a plane perpendicular to the second longitudinal axis, a larger        cross section when a first distance exists between the proximal        and distal parts compared to a when a second distance exists        between the proximal and distal parts, the second distance being        larger than the first distance.

The discussion and function of the central/deformable portions and thedistal/proximal parts may be as those described above.

The deformable portion circumscribes a cross section or a crosssectional area by the outermost parts of the deformable part definingthis cross section or area. Naturally, the deformable part may compriseonly a thin layer/weave or the like of material so that the overallcross section of the deformable portion is a narrow, closed curve, butit may also have an internal structure in order to keep the deformableportion expanded so as to attach to the blood vessel. One general,preferred type of deformable portion is a pre-shaped elementautomatically expanding when in the vessel. In this situation, no innerstructure may be required to obtain the expansion.

In this context, the second longitudinal axis preferably may be an axisaround which the deformable portion or the central portion is symmetric.Also, it may be desired that the proximal and distal parts defineapertures at the second longitudinal axis, so that the guide wire mayextend through the proximal and distal parts along the secondlongitudinal axis. Usually, the first and second axes will be parallelor at least substantially parallel when the fixator is positioned in theblood vessel.

When forcing the distal and proximal parts toward each other from thesecond to the first position, the cross section circumscribed by thedeformable portion increases. This cross section may be the crosssection at one position along (in a plane perpendicular to) thelongitudinal axis or may be a mean cross section along the longitudinalaxis over the length or extent of the deformable portion or centralportion.

Usually, when positioned in the blood vessel, the expansion of thedeformable portion is limited by the blood vessel. Outside the bloodvessel, the expansion usually can take place for the deformable portionto reach cross sections larger than that of the blood vessel diameter ortype for which the deformable portion or fixator is intended.

In a preferred embodiment, the preventing means prevent the distal partfrom travelling beyond the distal end. In this respect, the proximalpart preferably is movable in relation to the distal part, the centralportion and the guide wire, so that the pulling force is exerted to thedistal part, which may, in the above fixator, cause the deformableportion to attempt to obtain a larger cross section and thus engage theblood vessel with a higher gripping force. The reason for this is thatthe attachment of the deformable portion to the blood vessel will act tohave the pulling force actually force the distal part toward theproximal part which is more fixed in relation to the blood vessel. Thus,as the grip or engagement increases when the guide wire is pulled, theforce with which the deformable portion engages the blood vessel, whenno or only little force is exerted, may be low or weak, which causesless damage to the vessel walls.

However, due to the fact that the pulling force in this situation actsbetween the distal part and the central portion, the central portionwill typically react by trying to increase the cross sectional area themost at the most distal parts. This increase is counteracted by theblood vessel wall, whereby a larger force is exerted thereto. This maynot be desired, and different manners exist of counteracting thiseffect.

In one situation, the central portion has a rest shape that:

-   -   circumscribes a first cross sectional area in a plane        perpendicular to the second longitudinal axis and at a first        position along the second longitudinal axis and    -   circumscribes a second cross sectional area in a plane        perpendicular to the second longitudinal axis and at a second        position along the second longitudinal axis,        wherein the second position is closer to the distal part than        the first position, the second cross sectional area being        smaller than the first cross sectional area.

In this context, a rest shape is the shape which the central portion haswhen no forces act on it (except possibly gravity), including forcesacting to force the distal and proximal parts toward each other, such aswhen the central portion is positioned on a table or horizontal surface.

Also, in this context, the first cross sectional area is at least 2%,such as at least 5%, preferably at least 7%, such as at least 10%,preferably as at least 15%, such as at least 20%, preferably at least40%, such as at least 60% larger than the second cross sectional area.

When this fixator is positioned in the blood vessel, the central portionmay or may not attach to the inner surface of the blood vessel at thesecond position with the smaller cross sectional area, when no or asmall pulling force is exerted. However, when a pulling force is appliedto the guide wire, the lower cross sectional area at the second positionpreferably acts to increase in size and/or have a more even forceexerted to the blood vessel along the length or area of the deformableportion or the central portion. As described above, the pulling of thedistal part primarily acts to increase the cross sectional area atpositions closer to the distal end.

Preferably, the second position is a position within or at a distance ofat the most 80%, such as at the most 60%, preferably at the most 40%,such as at the most 25%, preferably at the most 10%, such as at the most5%, preferably at the most 2% of an extent of the central portion or thedeformable portion along the second axis, from the distal end of thecentral portion.

In another situation, the central portion is adapted to, when theproximal and distal parts are forced toward each other along the secondlongitudinal axis:

-   -   circumscribe a third cross sectional area in a plane        perpendicular to the second longitudinal axis and at a third        position along the second longitudinal axis, and,    -   circumscribe a fourth cross sectional area in a plane        perpendicular to the second longitudinal axis and at a fourth        position along the second longitudinal axis,        wherein the third position is closer to the distal part than the        fourth position, the third cross sectional area being smaller        than the fourth cross sectional area.

As mentioned above, the cross sections of the deformable portion orcentral portion will be limited by the blood vessel. Thus, thissituation is normally seen when the fixator is outside the vessel andnot limited in that manner.

When the proximal and distal parts are forced toward each other with theabove-mentioned at least 0.1N, such as 0.2N, preferably 0.3N, such, as0.4N, preferably 0.5N, such as 0.6N, preferably 0.7N, such as 0.8N,preferably 0.9N, such as 1N, preferably 1.5N, such as 2N, preferably2.5N, such as 3N, preferably 3.5N, such as 4N, preferably 5N, it willexpand (obtain a larger cross sectional area) more at the fourthposition and thus not at the distal part. As indicated above,preferably, the third position is a position within or a distance of atthe most 80%, such as at the most 60%, preferably at the most 40%, suchas at the most 25%, preferably at the most 10%, such as at the most 5%,preferably at the most 2% of an extent of the central portion or thedeformable portion along the second axis, from the distal end of thecentral portion.

In general, the deformable portion may comprise a wire mesh or braidedwires. The wire density of the deformable portion preferably is between0.1 and 15 wires per mm, such as between 0.2 and 5 wires per mm,preferably between 0.5 and 3 wires/mm along the longitudinal direction.Also, the wire thickness may be between 0.01 mm and 1 mm, between 0.05mm and 0.5 mm, preferably between 0.07 mm and 0.2 mm.

In a preferred embodiment, 40 wires (0.1 mm diameter) are used in abraid having a maximum diameter of 7 mm over a length of 14 mm whenexpanded and which, in the non-expanded shape, has a length of 40 mm.

In one situation, the wire mesh/braid has a wire density of the wiremesh/braid being higher at one of the second position, the thirdposition, and a distal end of the central portion, than at one of thefirst position, the fourth position, and a proximal end, of the centralportion. In this situation, the higher wire density (number of wires perdistance unit along the second axis) will make the expansion (increasein cross sectional area) lower than where the wire density is lower; thehigher wire density makes the pertaining parts of the deformable portionmore stiff.

An alternative to or in addition to the wire density difference, thedeformable portion may comprise a wire mesh/braid, wherein a wirethickness of the wire mesh/braid is higher at one of a the secondposition, the third position, and a distal end of the central portion,than at one of the first position, the fourth position, and a proximalend of the central portion. This wire thickness increase will also makethe pertaining part stiffer.

A further alternative or addition is one comprising a circumferencelimiting element at one of the second position, the third position, anda distal end of the central portion. In this manner, the circumferenceand thus cross sectional area at the third position may be limited so asto exert only a predetermined force to the blood vessel. Any pulling ofthe guide wire will thus direct the force to other parts of thedeformable portion further toward the proximal portion.

In the following, preferred embodiments of the invention will bedescribed with reference to the drawing, wherein

FIG. 1 is a schematic illustration of a fixator according to a firstembodiment of the invention, when disconnected from a retrievingcatheter and with a delivery catheter retracted from the fixing part;

FIGS. 2 and 3 are schematic illustrations of the fixator in FIG. 1 indifferent situations of use;

FIG. 4 illustrates a second embodiment of a fixator according to theinvention;

FIG. 5 is an exploded view of the fixator in FIG. 4;

FIG. 6 illustrates a third embodiment of a fixator according to theinvention;

FIG. 7 illustrates a fourth embodiment of a fixator according to theinvention;

FIG. 8 illustrates the force exertion during attachment to the bloodvessel;

FIG. 9 illustrates the force exertion outside the blood vessel;

FIGS. 10-12 illustrate different embodiments of a deformable portion forthe present fixator; and

FIGS. 13-16 illustrate a surgical procedure using the present fixatorfor positioning a branched stent graft in the aorta of a person.

In the following description the terms “distal” and “proximal” are usedto denote the mutual location of two corresponding parts, wherein theheart is used as reference, such that anatomical structures that arecloser to the heart are denoted as proximal and details that are fartherfrom the heart are denoted as distal. For parts of a medical device,such as the present fixator, the definition is instead based on thesurgeon as reference. Hence, details that are closer to the surgeon aredenoted as proximal and details that are farther from the surgeon aredenoted as distal.

In FIG. 1, a first embodiment of a fixator 1 in accordance with theinvention is shown. The fixator involves a flow transparent retainer orfixing part 2, which in the shown embodiment consists of a metal framebasket. The fixing part 2 is arranged on a guide wire 3. In FIG. 1, adistal tubular sleeve 5 is arranged at the distal end 2 a of the fixingpart. The distal sleeve 5 is fixed (releasably or not) to the guide wire3, or at least prevented from leaving the guide wire, whereas theproximal end 2 b of the fixing part 2 is arranged to slide over theguide wire 3 by means of a proximal tubular sleeve 4. The proximal anddistal sleeves 4 and 5 jointly limit the possible deformation of thefixing part 2 as its ends 2 a and 2 b are forced toward each other,which will be described below. The distal end 2 a of the fixator 1comprises a distal end part 6, which may be a continuation of the guidewire 3, and which is soft and pliable in order not to cause damage inthe target vessel. Guide wires for catheterisation are typically of thedimensions between 0.14 and 0.89 mm in circumference. These are verypliable and atraumatic with a hydrophilic slippery surface that allowscatheterisation of small, stenotic and kinked arteries, without damageto the target vessel wall.

The proximal end 2 b of the fixing part 2 involves a connecting member 7for connecting the fixing part 2 to a retrieving catheter 10. In theshown first embodiment, the connecting member 7 has internal threadsthat are arranged on the inside of the proximal tubular sleeve 4. Theretrieving catheter 10, on the other hand, comprises a correspondingconnecting member 11 in the form of external threads for mutualconnection of the retrieving catheter 10 and the fixing part 2.

In general (see FIG. 10), the fixing part or deformable portion 2 has acentral portion C, which attaches to or engages the vessel whendeployed, and which is connected to the sleeves 4/5 via the end portions2 a and 2 b.

Preferably, the fixator 1 also has or is supplied with or inside adelivery catheter 20 in the form of a hose of a diameter adapted tohouse the fixing part 2 and the retrieving catheter 10. The deliverycatheter 20 enables the positioning of the fixing part 2 as it allowsthe fixing part to be fully housed therein during the introduction andpositioning of the fixator 1. It would however also be possible to keepthe fixing part collapsed without housing it inside a delivery catheter20, e.g. by keeping the sleeves separated from each other by means ofe.g. a screw controlled arrangement.

The length of the guide wire 3, the retrieving catheter 10 and thedelivery catheter 20 must be sufficient to allow their respectiveproximal ends to be accessible to and manoeuvrable by the surgeon whenthe corresponding distal ends are located in a target vessel. Typically,the guide wire 3, the retrieving catheter 10 and the delivery catheter20 all have lengths between 0.5 and 2.8 meters.

The function of the fixator will be described step by step in anexemplary mode of use and with reference to FIGS. 2-4. A furtherdescription is found in relation to FIGS. 13-16.

In a first step, as shown in FIG. 2, the delivery catheter 20 isinserted into a target vessel 30, defined by a vessel wall 31 and anopening 32 into e.g. the aorta. During the insertion of the fixator 1,only the pliable distal end part 6 of the fixator 1 extends outside ofthe delivery catheter 20. The fixing part 2 is undeployed or collapsedin the radial direction such that it fits inside the delivery catheter20. In order to allow for the radial collapse, the fixing part 2 isextended in the axial direction with the distal sleeve 5 at a relativelylarge distance from the proximal sleeve 4. During the insertion, theconnecting member 7 of the fixing part 2 is connected to the connectingmember 11 of the retrieving catheter 10. The insertion of a catheterinto an unblocked vessel is in itself conventional and is therefore notdescribed in detail in this application.

In a second step, when the delivery catheter 20 is located inside thetarget vessel 30, the fixing part 2 is pushed out from the inside of thedelivery catheter 20. The pushing of the fixing part 2 is achieved bymeans of mutual movement of the delivery catheter 20 on the one hand,and the retrieving catheter 10 on the other hand. As the fixing part 2exits the delivery catheter 20 it strives to regain its original shape,which is individually adapted to the diameter of the vessel 30 such thatit exerts a certain pressure on the vessel wall 31. This pressure shouldbe as low as possible in order not to harm the vessel, but it musthowever be sufficient to keep the fixator from moving with respect tothe vessel. The fixing part 2 has a flow transparent form that allowsnutritive blood flow through it. In the present embodiment, the fixingpart 2 comprises crosswise woven threads, which are adapted to expand toa diameter that is slightly larger than an inside diameter of therelevant blood vessel so as to exert a pressure on the blood vessel wallthat restrains the fixing part 2 from moving with respect to the targetblood vessel 30. The blood flow is allowed to flow through the crosswisewoven threads.

Even though it is possible to provide the fixing part 2 with means forobtaining the expanded shape, it is preferred that the fixing part, andhere the crosswise woven threads, has an expanded rest shape, so thatthe expansion merely is a movement toward the rest shape. This type offixing part may be obtained by providing the threads in the desired,expanded shape and heat treating the threads to have or give thisexpanded shape the rest shape.

A third step, where the fixing part 2 is fully deployed outside thedelivery catheter 20 and at location inside the target vessel, isillustrated in FIG. 3. In this third step, the retrieving catheter 10 isdisconnected from the fixing part 2. In the present embodiment, thisdisconnecting is achieved in that the retrieving catheter 10 is rotatedwith respect to the fixing part 2, which is restricted from rotating dueto its contact with the vessel wall 31, such that the connecting member11 of the retrieving catheter 10 is unscrewed from the connecting member7 of the fixing part 2.

In a fourth step, when the retrieving catheter 10 has been disconnectedfrom the fixing part 2, both the retrieving catheter 10 and the deliverycatheter 20 may be withdrawn from the target vessel and leaving only thefixing part 2 and the guide wire 3 in the vessel 30. The fixing part 2is arranged to not hinder the blood flow through the vessel.

In order to ensure that the fixing part 2 is not disconnected from theguide wire 3 when the guide wire 3 is pulled, the proximal sleeve 4and/or the distal sleeve 5 is releasably fixed to the guide wire 3, suchas via a threaded connection, a snap fit or the like.

FIG. 4 illustrates a second embodiment of a fixator according to theinvention.

Naturally, details corresponding to details of the first embodiment aredenoted with the same reference numerals, whereas details that aredifferent from details of the first embodiment but that have the samefunction are denoted with the same reference numerals with an addedapostrophe. A number of differences exist both in construction and useof the first and second embodiments. It is clear that such features, maybe interchanged between the embodiments if desired.

In the second embodiment of the fixator 1, the threaded attachmentbetween the proximal sleeve 4 and the retrieving catheter 10 of FIG. 1is replaced by a snap-on lock, including a connecting member 11′ on theretrieving catheter 10 in the form of a claw like grasping unit withclaws or projections 16 and a corresponding connecting member 7′ in theform of a ring shaped stopper on, or in connection to, the proximalsleeve 4. The shape of the projections 16 is adapted to interlock withthe ring shaped stopper as the connecting member 11′ is retracted intothe delivery catheter 20, and as the delivery catheter 20 is pushed overthe connecting member 11′. Thus, the delivery catheter forces theprojections to grasp over the connecting member when the fixator isretracted towards the retrieval catheter by the guide wire.

In FIG. 4, individual threads/wires 12 of the basket shaped fixing part2 are clearly visible. The threads/wires 12 may be welded together atcrossing points 13, or they may be braided such that they pass eachother by turns over and under each other. The ends 14 of the threads aresecurely fastened to the sleeves 4 and 5, respectively, either bywelding, gluing or sewing or in any other suitable manner. Further, inFIG. 4, the connecting member 7′ in the form of the ring shaped stoppermay be seen inside the claw like grasping unit that constitutes theconnecting member 11′ on the retrieving catheter 10.

In the second embodiment, both sleeves 4 and 5 are arranged to slideover the guide wire 3. However, a stopper 8 positioned on the guide wire3 prevents the sleeves from moving over the distal end of the guide wire3 and thus disconnect fully from the guide wire 3.

Alternatively, the distal sleeve 5 may be detachably fixed, using e.g.any of the fastening methods between catheter 10 and sleeve 4. Thereason for this detachability or slidability will be described furtherbelow.

Further, from this view it is apparent that the function of the sleevesis somewhat different in this embodiment with respect to their functionin the first embodiment. In this embodiment, the connecting member 7′ isarranged directly on the proximal sleeve 4 of the fixing part. Theproximal sleeve 4 is partly and fixedly housed inside a protectivesleeve 15 (see also FIG. 5), which extends inside the basket shapedfixing part 2 and also partly houses the distal sleeve 5. When thefixing part 2 is in its deployed shape, there is a gap between thedistal and the proximal sleeves 5 and 4, respectively. As the guide wire3 is pulled, or the fixing part 2 is allowed to expand toward its restshape, the fixing part 2 is fixed to the vessel wall, and any pullingforce applied to the distal sleeve 5 will thus act to compress thefixing part in the axial direction. Thus, the sleeves move closer toeach other, until the proximal end 5 b of the distal sleeve 5 reachesthe distal end 4 a of the proximal sleeve 4. The contact between theseends of the sleeves thus limits the axial deformation of the fixing part2. The distal end 5 a of the distal sleeve 5 is arranged to interactwith the stopper 8 on the guide wire 3 and limit the axial movement ofthe guide wire 3 with respect to the fixing part 2, as described above.

In a third embodiment the guide wire 3′ is a hypotube, as is shown inFIG. 6. The hypotube may be made of Nitinol or stainless steel and ispreferably coated by a hydrophilic coating, such as e.g. PTFE, in orderto create a slippery contact surface to the retrieving catheter 10. Thehypotube may be just as flexible as a guide wire, or more flexible. Thesuitable size of a hypotube may range from 0.5 mm to about 2 mm with awall thickness of about 0.04 to 0.2 mm.

Preferably, the hypotube should have a sufficiently large inner diameterto successfully house a stiff conveying wire 25. The stiff conveyingwire 25 is helpful for guiding the insertion of the fixator 1. In orderfor the guide wire 3′ to be rerouted, it has to be flexible and pliable.

However, due to the pliability of the guide wire 3′, it may be difficultto control the guide wire 3′ and to guide it into the target bloodvessel. Hence, the stiff conveying wire 25 will make it possible tocontrol the guide wire 3′ during insertion. The conveying wire 25enables the insertion of further catheters and or stent branches overthe guide wire. With a stiff conveying wire inside the guide wire 3′,the stent graft branch can be introduced over the (hypo-)tubular guidewire 3′ housing a conveying wire.

The stiff conveying wire 25 may be withdrawn from inside the guide wire3′ when the fixing part 2 has been located in the target vessel 30. Whenthe stiff conveying wire 25 has been withdrawn from inside the guidewire 3′, the guide, wire is sufficiently pliable and flexible to bererouted inside an arterial system in an atraumatic manner.

The guide wire 3′ may be provided with an opening 26 near its distalend. With such an opening 26 the guide wire 3′ may constitute a conduitfor locally distributing a pharmaceutical via said opening 26. In manysituations, e.g. when treating tumours, it is of interest to deliver apharmaceutical agent locally, especially since certain pharmaceuticals,although effectively treating a disease process at one location, may beharmful if distributed systematically. Until now there has been noreliable way of delivering a pharmaceutical endovascularily over aperiod of time.

By means of a guide wire 3′ in the form of a hypotube comprising afixing part 2 it is possible to fix the end of the hypotube inside atarget vessel, and to deliver a desired amount of a pharmaceuticalthrough the opening 26 at the desired location, without risking that thehypotube will move and lose this location.

Naturally, the fixator of FIG. 6 may, for most parts, be similar to thefixator according the first and second embodiments. For example, astopper 8 may be provided on the guide wire 3′ for interaction with thedistal sleeve 5, and a protective sleeve 15, which extends inside thebasket shaped fixing part 2, is arranged to partly house the distalsleeve 5. Further, the distal end 6 of the guide wire 3′ is preferablysoft and pliable in order not to cause damage inside the body. Also, theproximal part of the guide wire 3′, e.g. proximal to the fixing part 2,is also pliable in order to allow rerouting. In a conventional manner,the tip of the guide wire 3′, may include a 180° bend (not shown) thatprevents arterial damage in the target vessel.

FIG. 7 illustrates a fourth embodiment of a fixing, part 2′ for use in afixator according to the invention. This fixing part 2′ has the shape ofa helical spring and is still releasably fixed to the guide wire 3 witha stopper 8′. The distal end of the fixing part 2′ may have aring-shaped element through which the guide wire 3 extends and whichengages with the stopper 8′ to prevent the fixing part 2′ from movingover the distal end of the guide wire 3. This fixing part 2′ has theadvantage of being extremely simple in manufacture as well as presentingvery little flow resistance in the blood vessel.

Introduction and retraction of the fixing part 2′ may be performed usinga catheter. Withdrawing the pre-formed fixing part 2′ will simply rotatethis without scraping or damaging the vessel wall.

In the present embodiments the fixing part 2/2′ preferably comprises ametal structure of weaved, coiled and/or braided wires or threads,preferably from Nitinol. Other biocompatible materials with similarproperties may also be used, e.g. other alloys or plastics. The materialmust be sufficiently flexible to allow it to be collapsed without beingplastically deformed, but at the same time sufficiently rigid to exert apressure when released inside a vessel. In a specific method ofproducing the fixing part 2/2′, a Laser cut length of a braided Nitinoltube is drawn around a template of a desired shape. The ends of theNitinol tube are shrunk around the ends of the template and a heattreatment is performed in this position, such that the Nitinol basket,i.e. the fixator, adapts to this new shape. The fixator will then striveto regain this shape whenever unaffected by exterior forces.

Alternative fixing parts 2/2′ may have a larger general contact areawith the blood vessel, such as when using a piece of cloth, material orthe like, which is supported on the coiled spring or the braided wire soas to better even out or enlarge the actual contact surface between thefixing part and the blood vessel wall.

As will be described in more detail below, the advantageous arrangementof the above embodiments enables the fixing part to remain in place asthe guide wire 3 is subject to tension, e.g. from rerouting of itsproximal end. The proximal sleeve 4 is arranged to slide on the guidewire 3 such that it remains unaffected by it, whereas the distal sleeve5 is prevented from travelling toward the distal end of the guide wire3. Due to this arrangement any pulling forces on the guide wire 3 willcompress the fixing part 2 in the axial direction, due to the frictionbetween the vessel wall 31 and the proximal part of the fixing part 2,such that the fixing part 2 is expanded in the radial direction, seeFIG. 8. Hence, the pressure against the vessel wall 31 will increase asa function of the pulling force on the guide wire, such that theincreased friction force between the fixing part 2 and the vessel wall31 instantaneously increases with the increased pulling force.Therefore, by means of the increased friction force, the fixing part 2is kept in place.

This arrangement allows for the fixing part to exert only a minimumforce on the vessel wall 31 as long as it is unaffected by any pullingforce, in order to minimise the traumatic effect on said vessel. Also,during most parts of a normal operational procedure, the guide wire isnot affected by any forces at all. The function of the fixator 1 ismainly to retain the position inside the target vessel. Pulling forcesnormally only arise when the guide wire 3 is being rerouted. The axialcompression of the fixing part may be limited by interaction of thesleeves 4 and 5, as they come into contact with each other in responseto a pulling force on the guide wire 3. Hence, the maximum radialextension of the fixing part 2, and thus the maximal radial forceexerted by it on the vessel wall, can be limited by the availabledistance between the sleeves; the greater the distance, the greater thepossible axial compression and consequent radial extension.

It has been found, however, that even though, as is seen in FIG. 8, thefixing part 2 is bounded perpendicular to its longitudinal axis, of thedimensions (primarily thickness or radius) of the blood vessel 30, theremay be a difference along the longitudinal direction of the forceexerted to the blood vessel. The cause is that as the fixing part ordeformable portion 2 engages the vessel wall 31 and the distal sleevepulled, the force is not distributed evenly over the area engaged by thefixing part 2 but mainly at the distal part thereof. In FIG. 9, theshape of a fixing part 2 in an element more flexible than a blood vesselis illustrated. It is seen that the cross sectional area (or radius ifcircular or having rotation symmetry) at the longitudinal position A islarger than at position B which is positioned more proximal than A.

Thus, in order to distribute this force more evenly, different solutionsare illustrated in FIGS. 10-12.

In FIG. 10, the fixing part 2 has an asymmetric shape, when non-stressedand/or in a non-compressed state, over the longitudinal length which isto engage the blood vessel, where a part of the fixing part 2 closer tothe distal end or sleeve 5 has a smaller cross sectional area (or radiusif circular or having rotation symmetry) at position A than closer tothe proximal sleeve 4, such as at position B.

Thus, when positioned in the blood vessel 30 and without pulling theguide wire 3, the shape of the fixing part 2 of FIG. 10 may look like inFIG. 8, where the force exerted to the wall 31 is uneven but still quitelow. When the guide wire 3 is pulled, however, the increased forceexerted on the wall 31 may be more even, as the more narrow rest shapeof the distal part (around position A) of the fixing part 2 will act tocounter-act a large expansion and thus force increase at that part.

In FIG. 11, the rest shape or non-stressed/non-compressed shape of thefixing part 2 may be symmetric but the expandability of the fixing part2 asymmetric along the longitudinal direction. In FIG. 11, the fixingpart 2 is provided as a wire mesh with a higher wire density at positionA compared to position B. Thus, when compressing the fixing part 2outside the blood vessel 30, an asymmetric shape as that illustrated inFIG. 10 may be obtained. Also, when compressing the fixing part 2 orpulling the guide wire 3 when the fixing part 2 is deployed in thevessel 30, the higher wire density at position A will act to even outthe pressure exerted and ensure that more force is applied aroundposition B.

Naturally, the same functionality may be obtained by adapting the wirethickness or other parameters of the wire mesh.

In FIG. 12, another manner is illustrated which prevents excessive forceexerting on the vessel 30 close to the distal end of the fixing part 2.In this embodiment, a circumference limiting element 40 is provided atthe distal end at position A. This element 40 prevents the circumferenceof the fixing part 2 from exceeding a predetermined length, whereby anyfurther deformation will be required at the more proximal parts, such asaround position B. This circumference limiting element 40 may be anon-stretchable element, such as a band, a wire or the like.

In general, it is noted that different types of materials for the fixingpart 2 and different constellations thereof may be chosen. The overallfunctionality is that the fixing part 2 should be able to engage thevessel wall while allowing a blood flow there through.

The overall advantages of using the present fixator 1 is now describedwith reference to FIGS. 13-16. This description of a use of the fixatoris limited to the positioning of a branched stent graft in a person totreat aortic aneurysms with aneurysm extension in the thoraco-abdominalaorta. It is noted that many other reasons exist for wishing tocatheterize blood vessels of small dimensions such as the renal arteriesto the kidneys, the visceral arteries to the intestines or the arteriessupplying the liver, etc. Accessing these arteries and maintaining acatheterization of these arteries is difficult especially whenconcomitant catheterisation of several arteries is taking placesimultaneously.

FIG. 13 illustrates the human artery system with the aorta 101 fromwhich a renal artery 102 feeds a kidney and an artery 103 leads toward aleg. As is usual in many of these procedures, the aorta 101 is accessedvia the common iliac artery 103 via an arterial puncture. Then, afixator with a fixing part 2 and a guide wire 3 is positioned asindicated above. The guide wire 3 extends out of the arterial puncture.

It is the goal of the procedure to position the graft 150 inside thesystem 100 with the main lumen 152 of the graft 150 in the aorta 101 andthe branch 154 toward and into the artery 102. The graft 150 has avertical longitudinal axis, openings at the upper and lower ends as wellas a side opening in the branch 154. In the graft 150, a transport wire162 is positioned which stretches through the main lumen 152 and thebranch 154 with ends 164 and 162, respectively.

In FIG. 14, the graft 150 has been positioned in the aorta 101.Conventionally, the graft 150 may be compressed, positioned within adelivery introducer and positioned in the aorta 101.

The graft 150 is introduced through the same artery puncture, and theends 162 and 164 extend outside the person together with the guide wire3. In this manner, the subsequent fixing/snaring is facilitated, as thismay be performed outside the body of the person.

Having positioned the graft 150 in the aorta 101, it is partly deployedin order to make the transport wire movable within the graft 150.

Subsequently, the guide wire 3 and the end 164 are attached to eachother, and the end 162 pulled, so that the guide wire 3 and end 164 arere-introduced into the system 100 and through the branch 154, the mainlumen 152 and out through the artery puncture so that (see FIG. 15) theguide wire 3 now extends from the fixing part 2 through the branch 154,the main lumen 152 and out of the patient. This procedure orre-positioning of the guide wire 3 will require some pulling of thefixing part 2, whereby its capability in this respect is used.

Having now ensured that the branch 154 is directed toward the artery 102(guided by the guide wire 3), the graft 150 may be fully deployed orextended/expanded so that it may, if desired, contact the wall of theaorta 101 and thus fix itself thereto. Also, subsequently, an extendergraft 156 is positioned (see FIG. 16) stretching from the branch 154 andinto the artery 102. This extender graft 156 is positioned using theguide wire 3 which already is positioned in the artery 102.

However, in order for the extender graft 156 to be able to actuallycover the part of the vessel wall 31 where the fixing part 2 engaged theblood vessel (which may have been slightly damaged during theprocedure), it is necessary to actually remove the fixing part 2 fromthe guide wire 3 before introducing the extender graft 156.

As the fixing part 2 is able to slide along the guide wire 3, this ispossible. The fixing part 2 is removed using a delivery catheter asdescribed above, while maintaining the guide wire 3 in place in theartery 102. Having then removed the fixing part 2, the guide wire 3 issubsequently used for introducing the extender graft 156 as illustratedin FIG. 16.

Naturally, more such grafts or grafts with more branches may be used.However, such use and positioning may be performed as described, withthe assistance of the use of the fixator and the re-routing of the guidewire 3 using the transport wire 160.

Also, the attachment of the guide wire 3 to the transport wire 160 maybe performed within the blood vessel of the person. Such intra corporealsnaring or attachment is a conventional procedure.

Alternatively, the fixators may be guided to the desired vessels alongany desired route and from different arteries, such as from the arteriesin the arms and legs. Then, when the tubular element has beenintroduced, guide wires and/or transport wires may be re-routed to allowthe desired attaching/snaring, where after the guide wires may extend tothe outside of the person through any opening desired. The use ofmultiple openings at different positions of the person may be desired inorder to prevent entanglement of the wires inside the person.

In one situation, the fixator is attached to the guide wire via anattaching wire which has the function of placing the fixator in thetarget vessel and retrieving it at the end of the procedure beforeplacing the stentgraft connection from the main graft 150 to the targetvessel.

The fixing part of the fixator according to the embodiments above may beprovided in different sizes, e.g. 5, 6, 7, 8, 9, 10, 11, 12, 13 14 mm indiameter, or fractions thereof, for use in arteries of correspondingdiameter. The collapsed fixing part 2 diameter is typically 8 French(2.67 mm diameter on the French catheter scale), and may vary from about6 to about 12 French (about 2 to about 4 mm), including sizes of 6, 7,8, 9, 10, 11, 12 French and half sizes there between, depending on thediameter of the delivery catheter to be used to house the fixing part.The size of the delivery catheter is accordingly also from about 6 toabout 12 French (about 2 to about 4 mm), including sizes of 6, 7, 8, 9,10, 11, 12 French and half sizes there between. The retrieving catheterhas a size that allows it to fit outside the guide wire and inside thedelivery catheter, e.g. from about 3 to about 10 French (about 1 toabout 3.3 mm), including sizes of 3, 4, 5, 6, 7, 8, 9, 10 French andhalf sizes there between. Usually, the guide wire and/or the hypotubeguide wire is very pliable and usually have a hydrophilic surfaceallowing catheterization of narrow, stenotic arteries without damage tothe target vessel.

One embodiment of the fixator may be one made of 40 braided 100 μmdiameter Nitinol wires provided as a, when compacted, 40 mm long elementwhich may be used in e.g. 5-7 mm blood vessels. When expanded in a 5 mmblood vessel, this fixator will occlude about 58% of the blood vesselcross sectional area, and the openings seen by the blood when flowingthrough the fixator will be 0.015-0.18 mm², whereas the occludingpercentage in a 7 mm blood vessel is about 47% and the openings0.06-0.25 mm².

It is noted that the branched graft 150 may be replaced by a so-calledfenestrated graft which has not branch(es) 154 but merely a sideopening. The positioning is similar in that the guide wire will extendfrom the fixator 2 through the side opening and out through the graft150 as described.

In that situation, the extender graft 156 may also be used, where it maybe desired to use a flairing graft having a larger diameter within thelumen 152 so as to ensure that the extender graft is fixed to the graft150 and is not allowed to release itself therefrom and move into thevessel 102.

Naturally, the graft 150 may have any number of branches 154 or sideopenings, and even a combination of one or more branches 154 and sideopenings

1. A method of positioning a tubular element having: a main tube havingan inner space defined between a first and a second end portion along alongitudinal axis of the main tube and at least an end opening at thefirst end portion from the inner space to surroundings of the main tube,a side opening positioned between the first and second end portionsbetween the inner space and the surroundings, a transport wire having afirst part, which extends from the inner space and out of the tubularelement through the end opening, and a second part, which extends fromthe inner space and out of the tubular element through the side opening,in a main blood vessel, having a branch vessel, of a person or animal,the method comprising: providing an assembly having a guide wire and afixator adapted to be releasably attached to an inner side of the branchvessel, the fixator being attached to the guide wire, which guide wirehas a distal end for introduction into the branch vessel and a proximalend, introducing the fixator into the branch vessel, via the main bloodvessel, and fixing the fixator to the branch vessel, providing thetubular element inside the main blood vessel so that the first part ofthe transport wire is engageable from outside the patient, fixing orattaching the second part of the transport wire to the guide wire, andpulling the first part of the transport wire to have the guide wireextend from the fixator through the side opening, the inner volume, andthe end opening.
 2. A method according to claim 1, wherein: the tubularelement comprises a branch tube attached to the main tube and openinginto the main tube, the side opening being an opening from thesurroundings into the branch tube, and the second part of the transportwire extends from the inner volume of the main tube and out of thetubular element through the branch tube and the side opening.
 3. Amethod according to claim 1, wherein the pulling step comprises havingthe guide wire finally extend to the outside of the person.
 4. A methodaccording to claim 1, wherein: the introducing step comprises the stepof having the guide wire of the fixed fixator extend to the outside ofthe person, the providing step comprises having also the second part ofthe transport wire extend to the outside of the patient, and thefixing/attaching step comprises fixing or attaching the second part tothe guide wire outside the person.
 5. A method according to claim 1,wherein the fixing/attaching step comprises fixing or attaching thesecond part to the guide wire inside a blood vessel of the person.
 6. Amethod according to claim 1, wherein the step of providing the assemblycomprises providing an assembly in which the fixator may moveindependently of the guide wire, the assembly further comprising meanspreventing the fixator from travelling distally of the preventing meansor beyond the distal end of the guide wire, the method furthercomprising the steps of, subsequent to the pulling step: removing thefixator while maintaining the distal end of the guide wire inside thebranch vessel, and introducing another element along the guide wire. 7.A method according to claim 6, wherein the introducing step comprisesintroducing another tubular element along the guide wire and positioningthe other tubular element so as to extend from inside the tubularelement and into the branch vessel.
 8. A method according to claim 7,wherein the positioning step comprises positioning the other tubularelement so as to cover an area of the branch vessel where the fixatorwas fixed.
 9. A method according to claim 1, wherein the main bloodvessel has a plurality of branch vessels and wherein: the tubularelement has: a plurality of side openings, a plurality of transportwires, the first part of all transport wires extending from the innervolume of the main tube and out of the tubular element through the endopening and the second part of each transport wire extending from theinner volume of the main tube and out of the tubular element through aseparate side opening, the providing step comprises providing aplurality of the assemblies, the introducing step comprises introducinga fixator into each of the branch vessels and fixing the fixators in thebranch vessels, the fixing/attaching step comprises fixing/attachingeach guide wire to a second part of a separate transport wire, where thebranch vessel in which the guide wire is fixed corresponds to the sideopening through which the second part extends, and the pulling stepcomprises pulling the first parts of the transport wires so as to havethe guide wires extend from the individual fixators through theindividual side openings and the inner volume of the main tube, the endopening, and toward the outside of the patient.
 10. A method accordingto claim 1, wherein the introducing step comprises introducing thefixator into a blood vessel of a person through a percutaneous openinginto the blood vessel, and wherein the providing step providing thetubular element inside the main blood vessel through the same opening ofthe person.
 11. A method according to claim 1, wherein the introducingstep comprises introducing the tubular element in a fully or partlycollapsed state, wherein the pulling step comprises positioning thetubular element within the main blood vessel, the method comprising thestep of, pursuant to the pulling step, bringing the tubular element fromthe fully or partly collapsed state and to a fully deployed state.
 12. Amethod according to claim 1, comprising the step of leaving the tubularelement in the person.